Process of case-hardening tantalum.



" TED STATES PATENT FFIC.

OTTO ABGHIBALD SIIVEPSON, OF CHARLOTTENBURG, GERMANY, ASSIGN'OR T0 SIEMENS & HALSKE A. G., 0]? BERLIN, GERMANY, A CORPORATION OF GERMANY.

PROCESS OF CASE-HARDENING TANTALUM.

No Drawing.

To all whom it may concern:

Be it known that I, O'rTo Anni-Imam SIMPSON, a subject of the German Emperor, and residing at Cha-rlottenburg, near Berlm, Germany, have invented a certain new and useful Improved Process of Case-Hardening Tantalum, of which the following 18 a specification.

The subject-matter of my invention is a process of case-hardening articles composed of tantalum.

According to my invention I treat the surfaces of such articles with a hardening agent, 0. g. oxygen, which is made operative either electrolytically or by heating in. the air; By treating such articles with oxygen or other hardening agents an exceedingly hard surface layer can be obtained. In order that this layer may penetrate deeper into the body than would be the case otherwise and simultaneously to enlarge the surface itself and with it the area on which the hardening agent can act, I roughen the surface, e. g. by means of a sand blast, before it is treated with the hardening agent. In

order then to make this hard surface resting on a softer, more ductile basis of tantalum cohere better and to work the hard mass rather more into the upper layers of the soft material, I may treat the roughened hardened surface in addition with presses or rollers. If unhardened parts of the lower layer become exposed durmg tlns treatment the surface may be hardened afresh when a materially improved result can be obtained.

By treating the hardened surface with presses or rollers the surface can. simulta neously be given the nature adapted for its later use; for example, by treating it with rough matrices or rollers bodies can be ob tained which mav serve as substitutes for Specification of Letters Patent.

Patented Nov. 8, 1910.

Application filed August 23, 1910. Serial No. 578,581.

diamond or emery disks or be used in the manner of files or the like. In this manner exceedingly thin disks, a fraction of :1 millimeter in thickness, can be made, for example, which have a rough, very hard surface and can be employed, for example, as separating disks for dental purposes.

I claim 1. The hereindescribed process of casehardening a body composed of tantalum, which comprises the steps of roughening the surface of the body and subsequently treating it with a hardening agent.

2. The hereindescribcd process of caschardening a body composed of tantalum. which comprises the steps of roughening the surface of the body and subsequently oxidizing the roughened surface.

The hereim'lescribed process of casehardening a bodv composed of tantalum, which comprises the steps of roughening the surface of the body, treating the roughened surface with a hardening agent and subjectingthe roughened hardened surface to pressure.

4. The hereindescribed process of casehardening a body composed of tantalum. which comprises the. steps of roughening the surface of the body, treating the roughened surface with a hardening agent, pressing the roughened hardened surface and subsequently again treating the surface with a hardening agent.

In testimony whereof I have signed mv name to this specification in the presence of two witnesses.

OTTO ARCHIBALD SIMPSON. 

